With the progress in automatic control techniques, automatic machine tool has already gone mainstream in the market. In general, the automatic machine tool may be equipped with different kinds and numbers of sensing elements for sensing the operation state of its components. In terms of rotating elements such as a rotating working table or spindles of the automatic machine tool, different kinds of sensing elements are required for sensing rotation speed, deflection, and load of the rotating elements. For example, a rotating encoder and an infrared tachometer may be used to sense the rotation speed of the rotating element, a pressure sensing device may be used to sense the load of a rotating element, and an eddy current sensing device may be used to sense the deflection of the rotating element.
However, said arrangement requires multiple sensing devices to be integrated into a single sensing module, which increases relevant costs and requires excessively large spaces. In addition, if one of the sensors is damaged and fails, then the sensing module has to be replaced or repaired and then can be operated as usual; that is, excessive kinds of sensors lead to low reliability. Moreover, the sensing module constituted by the multiple sensors is often arranged in embedding manner, such that the rotating element has to be dismantled to perform the replacement and the repair, which greatly increases labor costs and repair time.